The use of cooker extruders to cook raw cereal materials and work the cooked cereal material to form cooked cereal doughs is well known. Such cooked cereal doughs find particular suitability for use in the preparation of Ready-To-Eat ("RTE") cereal products and grain based snack foods. Cooker extruder usage provides numerous advantages in preparing such cooked cereal doughs. One of the main advantages of using such cooker extruders is a short cooking or residence time that allows for high throughput rates. High throughput rates, in turn, lower the cost of producing cooked cereal dough products. The residence time in a conventional extruder generally ranges from about three minutes to as short as about 20 seconds.
While the high throughput rates allowed by short residence time of the cereal material is an important advantage, such advantages come with a cost. Cooked cereal doughs processed for short times generally lack the desirable flavor that develops over the extended cooking times of certain other cooked dough technologies. Extruder cooked cereal doughs frequently exhibit a less than desirable "raw" or "green" flavor.
The art is replete with efforts to overcome the flavor deficiencies of extruder cooked doughs. In one approach, various flavorings or flavor precursors are added to the raw cereal feed materials. In another approach, supplemental equipment is employed to provide longer residence times to which the cereal material is exposed to elevated temperatures. For example, preconditioners are known for use upstream of a cooker extruder to aid in cooked cereal flavor development. Also, downstream of the extruder, for example, extended pipes or temper bins are known for use to promote flavor development.
Moreover, whether upstream or downstream, such equipment is generally designed to minimize the amount of shear such equipment imparts to the cereal dough. Close control of the amount of shear that the dough experiences is important to the eating quality of the finished cereal products. In particular, it is desirable to avoid the organoleptic annoyance of tooth compaction, which generally is aggravated with increasing exposure to shear.
The present invention provides an improvement in extruder cooker methods of preparing and/or toasting grain based products. Surprisingly, the improvement resides in part in the employment of extremely high speed screw rotation extruder cookers in combination with short barrel lengths. The present inventive extruder cooker methods are importantly characterized by extremely short residence times (i.e., .ltoreq.10 seconds) in combination with high mechanical energy inputs to provide grain based extruded products. Not only does the art teach away from using short residence time and high mechanical energy input, both individually and in combination, but also the present invention provides surprising advantages. In particular, the present methods are useful to provide grain based products that upon extrusion puff or expand. While "direct" expansion puffed cereals are known, the puffed grain based products made by the present invention are characterized by extremely small cell size and can be produced from either flour, grits, meal, or entire grain kernels that have not been reduced in their particle size and at their normal storage moisture content with minimum addition of water, for example about 3% based upon total weight. In addition to their novelty appeal, surprisingly, the grain based products according to the present invention also exhibit unexpected and beneficial texture, flavor and aroma properties. The grain based products according to the present invention exhibit improved textures and surprisingly little undesirable tooth compaction compared to identical formulations fabricated into conventional shapes such as puffed spheres, filament shreds or flakes.
Also, the usual grittiness and dark colors associated with cereals from whole grain flours are not present with the grain based products of the present invention.
Other advantages of the present methods and products are described below.